What does an aroma diffuser cost per month?

Most people work out whether they can afford the diffuser and forget the scent. The device is a one-off between roughly £40 and £193; the oil is a standing order that turns up every few weeks for as long as you keep using it. This page puts September 2026 prices against the run times the makers publish, shows the arithmetic, and is honest about the cases where no monthly figure can be produced at all.

One assumption runs through everything below: twelve hours a day, thirty days, so 360 hours a month. That is a device switched on when you get up and off when you go to bed. Halve it and halve the running costs.

The two costs, kept apart

Hardware. Paid once. In our comparison the water-based models sit between £39.99 (Beurer LA 40 at John Lewis) and £65.00 (Stoneglow at John Lewis). The Scentech models, converted from euros at checkout in September 2026, are about £101 for the Smart Aroma Diffuser, £132 for the Diffuser 2 and £193 for the Pro — and free from five, seven and nine scents respectively in the maker's own promotion, which is why many people never pay for the hardware at all.

Scent. Paid again and again. This is the number worth checking before you buy, and it is the one nobody puts on a product page.

What a Scentech pod costs per month

A ScentPod 2.0 is 65 ml for £27.00 in the UK shop, which is £0.42 a millilitre. Scentech states that a pod lasts one to three months depending on hours and intensity, and gives its own worked example: at twelve hours a day on a medium setting, well over two months; at sixteen hours a day on the highest setting, still a month.

So, using the maker's own figures and nothing else:

• Two months a pod → about £13.50 a month
• Three months a pod (a low setting, fewer hours) → £9.00 a month
• One month a pod (highest setting, sixteen hours a day) → £27.00 a month

At 720 hours across those two months, £27.00 works out at about 4p an hour. That figure assumes the manufacturer's stated pod life is right; nobody outside the company has verified it, and it is the single number in this article that most deserves your scepticism.

What a candle really costs, and why the comparison is unfair in both directions

Yankee Candle prices its Original Large Jar at £29.99 and says it gives up to 150 hours, which is 20p an hour. On the shop's own four-for-£85 offer that falls to 14p. At the other end, John Lewis lists the Jo Malone London Lime Basil & Mandarin 200 g candle at £56.00 with a stated burn time of 45 hours, which is £1.24 an hour — thirty-one times the cost per hour of a pod.

Two caveats belong with those numbers. Nobody burns a candle for twelve hours a day, so the monthly column is arithmetic rather than observation. And a candle is also light, a small ritual and an object on a table; if what you want is a warm glow on a Sunday evening, cost per hour is not the criterion and this table is answering the wrong question.

The comparison earns its keep in one specific case: when you are burning candles because you want the whole ground floor to smell of something, and finding that you need three of them. That is the point at which 20p an hour becomes 60p an hour and a diffuser starts to look like arithmetic rather than an indulgence.

Loose essential oil: why no monthly figure exists

A fair question: if a pod is £0.42 a millilitre and Holland & Barrett sells Miaroma lavender at £15.00 for 30 ml — £0.50 a millilitre — is loose oil not the same price or better? At Tisserand's organic 9 ml for £11.50 you are at £1.28 a millilitre, so the range straddles the pod either way.

But the millilitres are not doing the same work. An ultrasonic diffuser takes two or three drops in 100 ml of water, so a 30 ml bottle lasts a long time; a waterless diffuser consumes neat oil continuously. To turn either into pounds per month you need consumption per hour, and not one manufacturer in this comparison publishes it. John Lewis says two to three drops per fill and not how many fills a day; Tisserand says four to five hours per 100 ml fill and not how much oil goes in it. The running cost of a water-based diffuser is genuinely low and genuinely unquantifiable from published figures, and anyone giving you a precise monthly number for it has made it up.

What can be said is that the oil is not the main cost of owning one. The tank is: the filling, the emptying, the drying and the descaling.

Reed diffusers

Same problem, worse. No reed diffuser we looked at states a run time per hour or a room size, so its cost per hour cannot be worked out. Scentech states that its models cover ten to twenty-five times the area of reed diffusers — the manufacturer's own claim, not something we have verified. What is verifiable is the closest thing on our comparison page: the Stoneglow Modern Classics electric mist diffuser takes a 15 ml bottle at £11.00 which John Lewis states lasts up to ten weeks, or £0.73 a millilitre. Reeds are cheap, silent and forgiving in a cloakroom, and impossible to cost per hour.

A worked example: a two-bedroom flat

Suppose the sitting room and kitchen run together at about 45 m², the diffuser is on twelve hours a day, and the hallway is the room you actually care about because it is where the flat first smells of anything.

One Scentech Diffuser 2 covers that on the manufacturer's stated 65 m². Hardware is about £132, or nothing if it comes with a seven-scent order. Scent is about £13.50 a month on the maker's twelve-hour example, so roughly £162 in the first year including the hardware, or about £162 in scent alone over a year if the diffuser was the free one.

The same hours from Yankee Candle Large Jars at 20p an hour would be about £72 a month, or £864 a year, with something to light and extinguish twice a day. The ultrasonic route costs perhaps £40 to £55 for the device and an unquantifiable amount of oil, plus a jug of water carried through from the kitchen most days. Those three lines are the actual decision; everything else is a preference.

Four things that push the bill up

1. Running it on the highest setting. Scentech's own range runs from £9 to £27 a month on the same pod. The setting is what moves it.
2. Running it in an empty house. A schedule that follows the hours you are actually home is the single largest saving available, and it costs nothing.
3. Buying scent one bottle at a time. The free-diffuser thresholds at Scentech run at three, five, seven and nine scents, so the device is effectively paid for by an order you were going to place across the year anyway — provided you will genuinely use nine scents.
4. Exchange rates. Scentech's pound prices are conversions of its euro prices at checkout, not a fixed UK price list, so they drift. Every £ figure on this site carries the date it was read.

Our seven-model comparison puts these costs next to coverage, noise and review counts for each device: see the full ranking.